Flat biomedical electrodes are used in various applications. A common use is for transcutaneous monitoring of biological and physiological electrical potential associated with muscular activity. Flat electrodes are also commonly used for grounding patients during electrosurgery. The thickness of such electrodes may be less than 1 millimeter, or as great as 5 millimeters or more.
In medical and other applications, several differing types of connectors are used for conducting the electrical signal from the flat electrode to the measuring, recording, or grounding device. For best results and ease of operation, connectors desirably provide firm conductive connections, yet are readily removed from the electrode. In electrocardiographic applications, flat electrodes may be attached to patients for short-term diagnoses. Long term monitoring is also common, where the electrode is operatively connected to a monitoring device for several days. Unless the electrical connections are tight the patient's movements may stress the connecting cables sufficiently to pull the connectors from the electrodes. In addition, the connector should be held immobile on the surface of the electrode, since relative movement therebetween may produce artifacts in a signal.
One type of connector currently used in the medical field for attachment to flat electrodes is the well-known alligator clip, which depends on a small spring to provide the closing force. The holding force is transmitted through teeth on the jaws, rather than through flat surfaced jaws. Alligator clips tend to move on electrodes, and provide little surface contact for holding electrodes.
Another connector commonly used is the snap connector, in which a female member is snapped onto a circular male button. The female member may easily rotate on the male button and thereby produce artifacts on an electrical trace.
Bolduc, U.S. Pat. No. 3,624,590, shows a clamp for a flat grounding plate electrode, in which a spring provides the clamping force. Projections on one of the clamping jaws pass through holes in the electrode to lock it in place.
Lane, U.S. Pat. No. 3,475,717, describes an electrical connector for printed circuit boards in which a spring member in each side of the circuit board is actuated by a movable member. Contact between the springs and the circuit board is limited to a downward projecting edge of the springs.
Another form of connector is shown in Bast et al., U.S. Pat. No. 4,061,408. An integral electrically conductive sheet is motivated downward to a closed position by a lever arm for holding a plate electrode. The holding force is exerted along a narrow strip where the rounded end of the lever contacts the conductive sheet.
Bolduc, U.S. Pat. No. 3,842,394, shows an electrical connector for a grounding plate electrode in which the jaws are closed by a hand actuated clamp moving against a coil spring. The clamp handle may be turned to adjust the holding force, and a projection may be used to pierce the electrode to hold it in place.